Arbuscular Mycorrhizal Fungi Ameliorate Selenium Stress and Increase Antioxidant Potential of Zea mays in Seleniferous Soil

The indigenous arbuscular mycorrhizal fungi (AMF) spores were isolated from rhizosphere soil associated with maize plants grown in natural selenium-impacted agricultural soils present in north-eastern region of Punjab, India (32 degrees 46 ' N, 74 degrees 46 ' N), with selenium concentration ranging from 2.1 to 6.1 mg kg(-1) dry weight, and their role in plant growth promotion, mitigation of selenium stress and phytochemical and antioxidant potential of host maize plants in natural seleniferous soil were examined. Soils with selenium content between 2 and 200 mg kg(-1) and producing plants with 45 mg selenium kg(-1) dry weight are considered seleniferous soils. AMF inoculum consisting of indigenous AMF spores multiplied in pot cultures were inoculated to maize seeds at the time of sowing alongside control maize seeds in a total of 12 plots (6 replicates) made in seleniferous agricultural fields and sampled at maturity, i.e. 3 months. A significant difference was observed in plant growth parameters between control and AMF-inoculated maize plants. AMF-inoculated plants had 24.0 cm and 101.1 cm higher root and shoot length along with 27.2 g, 119.4 g and 28.1 g higher root, shoot and maize cob biomass in comparison to control plants. Se uptake studies through measurement of the emission spectrum of piazselenol complex by fluorescence spectrometry revealed that AMF inoculation led to 6.3 mu g g(-1) more selenium accumulation in mycorrhizal maize roots in comparison to control roots but lesser translocation to shoots and seeds, i.e. 17.17 mu g g(-1) and 19.58 mu g g(-1) lesser. AMF increased total phenolic content by 13 mu g GAE mg(-1) and total flavonoid content by 13.4 mu g QE mg(-1) in inoculated maize plants when compared to control plants. Antioxidant studies revealed that AMF inoculation also led to significant rise in enzyme activities by a difference of 115 and 193 EU g(-1) in catalase, 140 and 93 EU g(-1) in superoxide dismutase, 15 and 37 EU g(-1) in ascorbate peroxidase and 19.8 and 23.6% higher DPPH radical scavenging activities, respectively, in shoots and roots of plants with AMF inoculation. The findings of this study imply that AMF inoculated to maize plants in seleniferous field boost their plant growth and phytochemical and antioxidant properties, as well as minimize Se bioaccumulation in shoots and seeds of plants inoculated with AMF in comparison to control plants.